Apparatus for obtaining uniform superheating temperatures with various boiler loads



APPARATUS FOR OBTAINING UNIFORM SUPERHEATING TEMPERATURES WITH VARIOUSBOILER LOADS Filed Feb. 24, 1937 3 Sheets-Sheet 1 Dec. 24, 1940. H.VORKAUF 7 2,226,270

IN V E N TO R HEM km l/akm UF.

ATTORNEYS Dec. 24, 1940.

v H. VORKAUF APPARATUS FOR OBTAINING UNIFORM SUPERHEATING TEMPERATURESWITH VARIOUS BOILER LOADS Filed Feb. 24, 1937 3 Sheets-Sheet 2ATTGRNRLYS Patented Dec. 24, 1940 'OBTAINING UNIFORM TEMPERATURES WITHAPPARATUS FOR suraanmrmo PATENT OFFICE:

VARIOUS BOILER- LOADS Heinrich Voi'kau f, Berlin, Germany, assignor to ILa Mont Corporation, New York, N. Y., a cor- I poration' ofNew York 7Application Februar 24, 1937, Serial No. 127,380

. l InGermany February 28, 1936 reason of the great velocity and ;thegreater This invention, relates .to apparatus for obtaining uniformsuperheat. temperatures with .varying boiler loads. The invention aimsparticularly so to arrange the steam generator and superheater heatingsurfaces, preferably. contacted in like manner by the heating gases,that, as the flow of the products of combustion varies with varying.boiler loads, a higher heat reception by the superheater willbe-effected with small loads than with higher loads.

In accordance with the boiler constructionart and the. heating art, theapparatus for carrying out the process can be constructed invariousways. It is substantially essential that the steam generator andsuperheater surfaces be contacted in like manneryifor example, that theproducts of combustion flow through the generator transversely to thetubes and through-the superheater likewise transversely to the tubes orthat they flow, in both cases, lengthwise of the tubes. V

In accordance with the invention, the superheater is so constructedthatit possessesin' its various parts a variable capacity for':taking upheat and it is arranged in such manner that the part of the superheaterwhich is locatedinthe parts of the boiler flue through which the com--bustion gases principally flow at smaller loading has a larger capacityfor taking upbeat-than the part of the superheater located in otherparts of the boiler flue. I

In a boiler having aburner operating at right angles to the gas flow andwhich gives a shorter flame at smaller loads than at higher loads, the?superheater heating surface, according to the invention, is greater inthe part of the boiler flue lying adjacent to the front wall of theheating chamber than in the part next to the back Wall.

When firing with several burners, the arrangement is preferably suchthat in the surfaces contacted by the burners remaining in operation theratio of the superheater heating surface to the generator heatingsurface is greater than in the other parts of the boiler flue.

If in its course through the heating chamber a reversal of the directionof the gas flow is PTO! vided, then, according to the invention, at theturning edge a relatively large superheater heating surfaceis providedand in the outer part of the bend the generator heating surface isprincipally located, so that, by small loads, the products of combustionflow, under the less effective draft, principally through thesuperheater heating surfaces, while with bigger loads, by

resistance the flow willtake place more through thegenerator-heatingsurfaces. 1 Constructions according to this inventionfind especiallyadvantageous application with steam generators havingforced circulation of the water because with these any desiredarrangement of the steam generator heating surfaces and therewith alsoof the superheater heating surfaces is possible. Q I

Figure 1 is a vertical section through a steam generator of the forcedcirculation type having the present invention embodied therein; 1

Figure 2 is a vertical section through a steam generator also of theforced circulation typebut having a different arrangement of thetubesand flues, this steam generator being particularly adapted forpowdered coal firing;

Figures 3 and 4 are vertical and transverse sections through a marineboiler-with natural circulation and. having thepresent inventioniemebodied therein; Figure 5 is a vertical section through a boiler of theforced circulation type having a plurality of burners, one or more ofwhich may-beglcut' off when it is desired to operate at low. level.-

Figure 1 shows a section through'a steam generator with forcedcirculation of the water. The burner l blows horizontally into the firechamber 2, the combustionv gases being conducted 'vere tically into theflue 3. The tubes 4 form the steam generator heating surfaces, and thetubes 5 the steam superheating surfaces. The'illustrated greater area ofsuperheater heating. surface in the front part 'of the gas fluezis ,for'the purpose of drawing the greater part of the productsof combustionthrough the front part of. the gas flue when the burner,;by' smallloadingy'has ashorter flame. The larger superheating heating surfaces inthis part and the higher combustion gas temperature at the entrance intothe superheater have the result of effecting a high superheating atsmall loads.

If, however, the burner, at small loads, works with higher air velocityor, through the flow relations, a preponderating flow of the hot gasresults in the back part of the gas passage, it is then advantageous soto arrange the superheater heating surfaces in this part that they takeup more heat.

The step form arrangement of the superheater and generator surfacesillustrated in Figure 1 has also the advantage that. with possible lateralteration of the superheating, any desired increase or diminution ofthe coils 6 and 1 of the tion, drawn sharply about the turn, flowprincipally through the superheater heating surfaces. With higher loads,on the other hand, the gases mounting vertically in the fire chamberpenetrate more into the steam generator heating surfaces because oftheir greater velocity, while also, because of the higher resistancescaused by the greater gas masses, a uniform distribution over the entirecross section is effected.

Figures 3 andl show sections through a marine boiler, with naturalcirculation, in the tube bundles I4 of which superheater heatingsurfaces l5 are built in. The tube bundles are so arranged that asmaller number of boiler tubes lie before the superheater in the frontpart than in the back part.

According to the burner relations it is desirable to arrange thesuperheater surface nearer to the fire chamber either at the front or atthe back. If the air velocity in all burners diminishes with theloading,-then it is better to bring the superheater nearer the firechamber at the front with small loads, as shown in Fig. 4, because theflames then become shorter and are turned earlier into the tube bundle,the important thing, in the form of the invention illustrated in Figs. 3and 4, being to so locate the superheater tubes that the average depthof the screen of generator heating surfaces traversed by the products ofcombustion in the direction of their flow before contacting thesuperheater heating surfaces will be less with the smaller boiler loadsthan with the larger boiler loads.

In Figure 5 still a further arrangement of the superheater according tothe invention is illustrated, which is particularly suitable when, withoperation at a low level, one of the burners l8, I9, 20 is cut out. If,for example,'the middle burner 19 is to remain in operation, then thesuperheater heating surface is increased in the middle and the generatorheating surface is reduced. The tubes l6 are generator tubes and thetubes I! are superheater tubes.

The present invention is not limited to the described arrangement ofsuperheaters in which, through natural gas movement, a strongersuperheating takes placerat small loading.

The steam generator tubes "I2 What is claimed as new is:

1. Means for producing uniform superheat temperatures with varyingboiler loads comprising, in combination, superheater and steam generatorheating surfaces so arranged in a flue that both are contacted byproducts of combustion in like mannerand that they so supplement eachother across the flue ,as to produce substantially uniform draftresistance throughout the cross section of the flue, said superheaterand steam generator heating surfaces being also so arranged that, whenwith varying boiler loads there is a correspondingly varying flow of theproducts of combustion, the average depth of the screen of generatorheating surfaces traversed by the products of combustion in thedirection of their flow before contacting the superheater heatingsurfaces will be less with the smaller boiler loads than with the largerboiler loads.

2. Apparatus according to claim 1, in which the average depth of thesuperheater heating surfaces traversed by the combustion gases will begreater with the smaller boiler loads than with the larger boiler loads.

3. Means for producing uniform superheat tacted by the products ofcombustion will increase with the smaller boiler loads.

4. Means for producing uniform superheat temperatures with varyingboiler loads, compris- ,ing,,in combination, superheater and steamgenerator heating surfaces so arranged across a flue that they togetheroffer substantially uniform 'draftresistance throughout the crosssection of the flue, the ratio of superheater heating surface to steamgenerator heating surface so varying from one side of the flue to theother that, when with varying boiler loads there is a correspondinglyvarying flow .of the products of combustion, the ratio of superheaterheating sur- HEINRICH VORKAUF.

